The present invention is directed generally to machinery for can production and specifically to a cutter assembly for can fabrication.
In the manufacture of metal cans, it is conventional practice to form an unfinished can or container of cylindrical configuration comprising of a bottom and a cylindrical side wall which is open on the top end. Such unfinished can members can be formed by a variety of processes such as drawing and ironing to provide the unfinished container. After the container has been formed, it is necessary to trim the upper end of the container to achieve a finished container having a desired height and also having a smooth upper edge termination permitting connection to a top member. It is essential that the upper edge termination be essentially flawless since the upper edge is subsequently subjected to an outward flanging process for enabling the connection of the top to the container. Any burrs, cracks or the like in the edge termination can prevent obtainment of a good seal between the top and the can in the flange area so as to render the can useless and to also result in the waste of its contents.
Numerous prior art devices have evolved for the purpose of trimming the ends of unfinished containers. However, all of the presently known conventional devices employed in trimming can ends suffer from one or more deficiencies and/or drawbacks. For example, the device of U.S. Pat. No. 3,894,455 incorporates two rotary cutting knives with circular cutting edges into a replaceable cartridge. The first knife is attached to a fixed knife support. The second knife is attached to a transversely shiftable knife support. By rotating the shiftable knife support about a pivot axis parallel to the axis of the fixed knife support, the shiftable knife is swung into the cutting position. The replaceable cartridge was an improvement over the prior art but the cartridge utilized small precision components to control the transverse motion. Thus, it was unsuited for long term operation.
The inventions of U.S. Pat. Nos. 4,181,050 and Re. 30,746 describe cutter assemblies which are more compact than U.S. Pat. No. 3,894,455. Additionally, they disclose a method of improving the quality of the trimmed edge by canting the trimmer unit 2.0 degrees from the axis of the can. The canting is accomplished by wedging shims between the cartridge and the turret plate. Although these assemblies are an improvement over U.S. Pat. No. 3,894,455, they require a skilled technician to calibrate the canting. Additionally, this patent also disclosed a more robust method for controlling transverse motion.
An additional problem with the inventions of U.S. Pat. Nos. 4,181,050 and Re. No. 30,746 concerns the adjustment of the clearance between the fixed knife and the shiftable knife necessary when assembling the unit. In order to adjust the prior art assemblies, the assembly is first partially disassembled by a skilled technician. The technician then adjusts the clearance by inserting shims in the assembly. The assembly is then reassembled and the clearance is measured. If the clearance is incorrect, the process is repeated. Typically, the process is repeated several times. This calibration is time-consuming and adds a significant cost to the overall process.
U.S. Pat. No. 4,557,167 discloses that maintaining one of the knives sharp and applying a radius to the cutting edge of the other knife, the burr can be transferred to the scrap ring. However, the invention of U.S. Pat. No. 4,557,167 uses disk knives whose longitudinal axes are generally perpendicular to one another. Thus, it is bulky and not suited for use in a cartridge.
The prior art cutter assemblies are either too large and bulky or are complicated and require a skilled technician to calibrate. Therefore, it would be desirable to have a cutter assembly which is both compact in size and simple to calibrate.
The present invention provides a cutter assembly comprising a fixed-longitudinal-axis knife support shaft with a top end and a bottom end, a fixed-longitudinal-axis knife mounted adjacent the top of the fixed-longitudinal-axis knife support shaft, a moving knife support shaft, having a top end, a bottom end and a longitudinal axis, the moving knife support shaft disposed to pivot substantially perpendicular to the longitudinal axis, and a moving knife mounted adjacent the top of the fixed-longitudinal-axis knife support shaft, wherein the moving knife has a non-cutting position and a cutting position and the moving knife support is adapted to be pivoted to put the moving knife into the cutting position. Further, the invention may comprise at least one flexible hinge and at least one spring. It also may include a rocker arm and a striker plate.
The present invention also includes a cutter assembly comprising a fixed-longitudinal-axis knife support shaft with a top end and a bottom end, a fixed-longitudinal-axis knife mounted adjacent the top end of the fixed-longitudinal-axis knife support shaft, a moving knife support block, a moving knife support shaft with a top end and a bottom end, the moving knife support shaft pivotably mounted in the moving knife support block, a moving knife mounted adjacent the top end of the fixed-longitudinal-axis knife support shaft and at least one flexible hinge affixed to the moving knife support block, wherein the moving knife has a non-cutting position and a cutting position and is adapted so that in the non-cutting position the moving knife support shaft is tilted away from the fixed-longitudinal-axis knife support shaft by flexing the flexible hinge such that the separation between the top of the fixed-longitudinal-axis knife support shaft and the top of the moving knife support increases while the separation between the bottom of the fixed-longitudinal-axis knife support shaft and the bottom of the moving knife support shaft remains essentially constant. The flexible hinge maybe made of any resilient material, for example fiberglass.
The present invention also includes a cutter assembly comprising a fixed-longitudinal-axis knife support shaft with a top end and a bottom end, a fixed-longitudinal-axis knife mounted adjacent the top end of the fixed-longitudinal-axis support shaft, a moving knife support block, a moving knife support shaft with a top end and a bottom end, the moving knife support shaft pivotably mounted in the moving knife support block, a moving knife mounted adjacent the top end of the moving knife support shaft and at least one flexible hinge affixed to the moving knife support block, wherein the moving knife has a non-cutting position and a cutting position and is adapted so that in to cutting position the moving knife support shaft is tilted toward the fixed-longitudinal-axis knife support shaft by flexing the flexible hinge such that the separation between the top of the fixed-longitudinal-axis knife support shaft and the top of the moving knife support decreases while the separation between the bottom of the fixed-longitudinal-axis knife support shaft and the bottom of the moving knife support shaft remains essentially constant.
The present invention also includes a method of trimming a container with an inside and an outside comprising conveying the container to a cutter assembly, advancing the container a predetermined distance onto a fixed-longitudinal-axis knife mounted on a fixed-longitudinal-axis knife support so that the fixed-longitudinal-axis knife is inside the container and a movable knife mounted on a movable knife support is outside of the container, the movable knife being opposed to the fixed-longitudinal-axis knife, pivoting the moving knife about an axis perpendicular to the longitudinal axis of the moving knife support shaft to put the moving knife into a cutting position from a non-cutting position, and cutting the container.
Additionally, the present invention includes a method of trimming a container with an inside and an outside comprising conveying the container to a cutter assembly, advancing the container a predetermined distance onto a fixed-longitudinal-axis knife mounted on a fixed-longitudinal-axis knife support so that the fixed-longitudinal-axis knife is inside the container and a movable knife mounted on a movable knife support is outside of the container, the movable knife being opposed to the fixed-longitudinal-axis knife, pivoting the moving knife from a non-cutting position to a cutting position by tilting the moving knife support shaft toward the fixed-longitudinal-axis knife support shaft by unflexing a flexible hinge such that the separation between the top of the fixed-longitudinal-axis knife support shaft and the top of the moving knife support decreases while the separation between the bottom of the fixed-longitudinal-axis knife support shaft and the bottom of the moving knife support shaft remains essentially constant, and cutting the container.
The invention also includes a method of trimming a container with an inside and an outside comprising conveying the container to a cutter assembly, advancing the container a predetermined distance onto a fixed-longitudinal-axis knife mounted on a fixed-longitudinal-axis knife support so that the fixed-longitudinal-axis knife is inside the container and a movable knife mounted on a movable knife support is outside of the container, the movable knife being opposed to the fixed-longitudinal-axis knife, pivoting the moving knife from a non-cutting position to a cutting position by tilting the moving knife support shaft toward the fixed-longitudinal-axis knife support shaft by flexing a flexible hinge such that the separation between the top of the fixed-longitudinal-axis knife support shaft and the top of the moving knife support decreases while the separation between the bottom of the fixed-longitudinal-axis knife support shaft and the bottom of the moving knife support shaft remains essentially constant, and cutting the container. Further, the clearance between the fixed-longitudinal-axis knife and the cutting knife may be set with an adjustment screw.
Additionally, the present invention provides a cutter assembly for trimming a container with an inside and an outside comprising a fixed-longitudinal-axis cutting means mounted on a fixed-longitudinal-axis support means, a movable cutting means mounted on a movable support means, a means for advancing the container a predetermined distance onto a fixed-longitudinal-axis knife mounted on a fixed-longitudinal-axis knife support so that the fixed-longitudinal-axis knife is inside the container and a movable knife mounted on a movable knife support is outside of the container, the movable knife being opposed to the fixed-longitudinal-axis knife, a means for pivoting the moving cutting means from a non-cutting position to a cutting position by tilting the moving support means toward the fixed-longitudinal-axis support means such that the separation between a first end of the fixed-longitudinal-axis support means and a first end of the moving support means decreases in the cutting position while the separation between a second end of the fixed-longitudinal-axis support means and a second end of the moving support means remains constant.
The present invention also provides a cutter assembly for trimming a container with an inside and an outside comprising a fixed-longitudinal-axis cutting means mounted on a fixed-longitudinal-axis support means, a movable cutting means mounted on a movable support means, a means for advancing the container a predetermined distance onto a fixed-longitudinal-axis knife mounted on a fixed-longitudinal-axis knife support so that the fixed-longitudinal-axis knife is inside the container and a movable knife mounted on a movable knife support is outside of the container, the movable knife being opposed to the fixed-longitudinal-axis knife and a means for pivoting the moving cutting means about an axis perpendicular to the axis of the moving support means to put the moving cutting means into the cutting position from a non-cutting position.
The present invention also includes an apparatus for trimming containers comprising, a rotating turret for supplying containers and any of the cutter assemblies described above.